IBM iSeries 270 Service Manual page 593

What you should know about load source disks on systems with mirrored protection: For use by
authorized service providers.
v Local load source: A disk used as the source for IPL data.
Primary Partition:
– For system Models 270, 800, 810, 820, and 825: This disk unit must be located in position D01,
D02, D03, or D04.
– For system Models 830, 840, 870, 890, SB2, and SB3: This disk unit must be located in position
D31, D32, D33, or D34.
Secondary Partition:
– See Locating a Secondary Partition's Load Source From the Primary Partition's Console in the
iSeries Service Functions
information.
v Remote load source: A load source disk unit that is not a local load source. A load source that is not in
one of the positions described for 'Local load source'.
For systems in which both of the mirrored load source disk units are local load sources:
The system can use either disk as its source for IPL data. The disk that first reports to the service
processor is the one that is used. The system starts the IPL with this device and later synchronizes the
second load source disk with the first.
If the first load source disk fails after the Licensed Internal Code determines that the system has mirrored
protection, the Licensed Internal Code performs the IPL by using the second load source disk.
If the first load source disk fails before the Licensed Internal Code determines that the system has
mirrored protection, the IPL stops with a system reference code (SRC) displayed.
If the system starts the IPL on a load source disk that contains data which is back level compared to the
data on the other load source, the Licensed Internal Code attempts to start the IPL from the second load
source disk. If the second attempt fails, the IPL stops with an SRC displayed.
For systems in which one of the mirror load source disk units is a local load source, and one load
source is a remote load source:
The system can use only the local load source as its source for IPL data. The system starts the IPL with
this local load source device and later synchronizes the remote load source disk with the data on the local
load source. If the local load source disk fails, the IPL stops with a system reference code (SRC)
displayed.
Find the load source disks on systems with mirrored protection: For use by authorized service
providers.
When the system auxiliary storage pool (ASP1) has mirrored protection, the system has two disk units that
are load source disks.
Use the Work with disk units option under Dedicated Service ToolS (DST) or System Service Tools
(SST) to display the configuration.
Alternate IPL device: For use by authorized service providers.
Before continuing with this procedure, go to Determine if the system has logical partitions. If the system
has logical partitions, this procedure is for the Primary partition only. To locate the alternate IPL device for
Analyze hardware problems
581